A switchgear cabinet typically includes three compartments: a front equipment compartment, a middle bus compartment and a back cable compartment. The equipment compartment houses switching equipment, such as circuit breakers. The cable compartment houses the fixed power buses. The bus compartment (also referred to as a “wireway”) is arranged between the equipment compartment and the cable compartment, and routes power between the equipment and the power buses.
In addition to current overloads, the switchgear cabinet may encounter other hazardous conditions known as arcing faults (or “arc faults”). Arcing faults occur when electric current “arcs” or flows through ionized gas between conductors, e.g., between two ends of broken or damaged conductors, or between a conductor and ground in the switchgear enclosure. Arcing faults can result from corroded, worn or aged wiring or insulation, loose connections and electrical stress caused by repeated overloading, lightning strikes, vermin, dropped wrenches during maintenance, etc. Particularly in medium-to-high voltage power distribution systems, the ionized gas associated with arcing faults may be released at pressures and temperatures sufficient to severely damage or destroy the switchgear equipment and/or cause severe burning injuries or death to operating personnel.
The switchgear cabinet generally provides arc-resistant metal switchgear compartments, often with a means for venting the gases from the compartments in the event of an arcing fault. These compartments are designed to withstand the pressures and temperatures of the gases associated with an arcing fault and reduce the likelihood or extent of damage to switchgear equipment by preventing the gases from entering adjacent switchgear compartments. Safety to operating personnel is enhanced by channeling and venting the hot gases away from operating personnel. However, because these systems do not eliminate the generation and release of hot gases associated with arcing faults, they do not completely eliminate the risk of injury to operating personnel and/or damage to the switchgear equipment.
As a consequence, various arc fault detection systems have been developed to sense an arcing fault, and in response, to quickly interrupt the power supplying the arc. These types of systems incorporate the use of sensors, such as optical sensors, to monitor conditions in the cabinet which may reflect a presence of an arcing fault. The sensors, however, are often located and fixedly mounted in areas of the cabinet, such as the cable and bus compartment, that are not readily accessible for inspection, maintenance or replacement after the equipment is in service. In order to service the sensors, it may be necessary to disassemble equipment or other components of the cabinet, which can result in extended downtime and labor cost.